Vehicular reinforcing bar structures are known where a reinforcing bar (or cross beam) is fixedly fastened at opposite end portions thereof to left and right rear side frames (i.e., vehicle body frame members), extending in a front-rear direction of the vehicle near left and right wheels of the vehicle, to thereby enhance a mechanical strength of a rear section of the vehicle. One example of such vehicular reinforcing bar structures is disclosed in Japanese Patent No. 3670233.
According to the disclosure of the No. 3670233 patent, the reinforcing bar (cross beam) is a pipe-shaped member having flattened mounting portions at its longitudinally opposite end portions, and the reinforcing bar is fixedly fastened at the flattened end portions (mounting portions) to the left and right rear side frames (i.e., vehicle body frame 21) members). However, with the disclosed vehicular reinforcing bar structure, there is a need to enhance a load transmitting efficiency at the end portions (mounting portions).